I would not recommend a netbook because it is too small and not powerful enough. If you want portability buy a 12 - 14" and if you want to do more than wireless cracking buy one 15 - 17" with a resolution of minimum 1600x900.I recommend a good resolution, because you'll want to have more windows open in the same time (example: 2 shells and a browser, or a browser and burp...).

Also, don't put too much in a laptop unless you are rich.

For example, I just bought an used laptop, Dell Precision, core 2 duo, 4GB RAM, 17", SSD and I will use it for normal browsing and I have 2 OS windows and Backtrack.Next week I will buy a server, dual CPU XEON, 6GB RAM, 2HDD and I will put my VMs, I will use it also as an web server, as a test machine...

The total price - 650$

If you buy a good laptop 17", it will cost you more than 1000$, without any return on investment. Worst, in one year it's value will be 700$ max.

I am giving you these advices because I saw that you are on a budget. Otherwise... buy the most expensive MAC, put a Linux as a dual boot and .... you'll do the same work as I do

the two asus intel i3 laptops im looking at both 15.6 inch 4 gigs of ram. one has 500gig hd and 3 usb ports is 449$. the other one has 4 gigs 2 usb ports and 320 gig hd. and is 399 thease are at best buy where i have a card. im trying to decide which one to get really the one i like only has two usb ports. i like how respnsive the mouse is and such and it seems to have a better picture than the other. but ive got a blue tooth adatper a gps adatper and my alfa wirless adatper to get better signals.

At least Penetration tester should have a good performance Computer/Laptop. If you are going to buy low performance laptop then in future you will be having some problem(It happened for me)...

Some Problem if get a low performance laptop:

1. You need low budget for buying a Low performance laptop. So Screen may be lower than 14" and after some month you may loss your eye power ''' heh.2. What if you are going to crack a hash or a list of hash? Your laptop will be too slow and you will be unable to do others work at a time.3. multiple tasking will be boring.

In my opinion if you budget problem then wait for some time then go for "good".